Another Boeing 787 flight cut short on United

DALLAS (AP) — Mechanical glitches that caused three United Airlines flights to be cut short in the past week might have gotten little notice except for one detail: All the planes were Boeing 787s.

The 787, which Boeing calls the Dreamliner, faces more scrutiny than normal because it was grounded for three months by concern about overheating lithium-ion batteries.

Aviation experts say the three recent incidents with United planes didn’t appear to pose any threat to passenger safety. But, they say, the reputation of Boeing and its newest plane will suffer if glitches continue to pile up:

— On Sunday, a United 787 flight from Houston to Denver returned to Houston shortly after takeoff because of what United called “a brake indicator issue.” Spokeswoman Jennifer Dohm said the plane, with 219 passengers, made an emergency landing as a precaution. She said a maintenance team examined the plane, and it was returned to service.

— Last Thursday, a United 787 carrying 218 passengers from London to Houston stopped in Newark, N.J., because an indicator showed low engine oil. The Federal Aviation Administration said it was looking into the incident.

— Last Tuesday, a United flight from Denver to Tokyo diverted to Seattle because of what the airline called an oil filter issue. The airline put up about 200 passengers overnight in a hotel, then flew them to Tokyo the next day on another 787.

It’s not unusual for a new plane or model to suffer glitches. Some sound more ominous than others, such as when Airbus had to repair cracks on parts inside the wings of its huge A380 jets in 2011 and 2012.

With last week’s Dreamliner incidents, “We’re seeing a relatively small number of relatively minor problems,” said Richard Aboulafia, an aviation analyst with the Teal Group. “This is similar to what we’ve seen with other new aircraft.”

John F. Thomas of L.E.K. Consulting said three aborted flights in six days could be partly coincidence and partly due to pilots being quick to land if anything on the 787 seems out of the ordinary.

“Because of what happened with the batteries, people would naturally be cautious,” he said.

The Dreamliner is Boeing’s most technologically advanced airliner, with lightweight materials and other innovations designed to boost fuel efficiency.

The fuel efficiency makes it suited for long flights, including international routes. Its medium size — smaller than the Airbus A380 and Boeing 747 and 777 — gives airlines an alternative to the jumbo jets when serving secondary routes such as Denver to Tokyo. Lithium-ion batteries provide power to the plane, and they overheated on two planes in January, leading regulators to ground the entire worldwide fleet of 50 Dreamliners.

Aboulafia said last week’s incidents won’t cause airlines to shy away from the Dreamliner, but he thinks the battery issue still poses a potential threat to the plane’s reputation. The Federal Aviation Administration approved a Boeing redesign of the battery system and allowed the 787s to resume flying before the root cause of the overheating was determined.

“I would be concerned about the lack of a backup plan and the cost of swap-outs if there’s a high rate of failure with battery cells,” Aboulafia said.

Customers can still seek compensation from Boeing for the grounding. On Monday, Poland’s government said that Boeing will offer to compensate LOT, that country’s national airline, for the grounding of its two 787s earlier this year. A Polish official said LOT lost more than $30 million in business. Boeing declined to comment.

Jon Kettles, an aviation lawyer in Dallas, said even apparently minor incidents like those in the past week should be taken seriously, especially on new aircraft that haven’t flown much.

“The new scrutiny is warranted and necessary to catch problems in the early stages before they cause an accident,” he said.

Airlines are giving Boeing a vote of confidence.

At last week’s Paris Air Show, Boeing announced 102 orders and commitments for a new, larger model of the Dreamliner, the 787-10. The company has 930 firm orders for the three versions of the 787.

“The 787 is a great airplane and we know it will continue to receive heightened attention when reliability events occur in service,” said Marc Birtel, a Boeing spokesman.